Implementation Of Six-Step Motor Control Algorithm In Stm32 Nucleo Microcontroller; Introduction To Bldc Theory; Figure 1: Bldc Motor Control Sequence; Figure 2: Six-Step Phase Voltage With Bemf Sequence And Pwm Modulation - ST STM32 User Manual

Implementation of six-step motor control
algorithm in STM32 Nucleo microcontroller
3 Implementation of six-step motor control algorithm
in STM32 Nucleo microcontroller
3.1

Introduction to BLDC theory

A brushless three phase motor is made of a fixed part (a three winding set called "stator")
and a mobile part (containing a permanent magnet called "rotor").
In BLDC motor control, the electrical cycle is subdivided into six commutation steps. For
each step, the bus voltage is applied to one of the motor three phase windings whereas the
ground is applied to a second winding. The third winding remains open. The successive
steps are executed in the same way except that the motor phase winding changes to
generate a rotating stator field (see
arrow shows the stator flux vector rotation of and the blue arrow shows its direction.
A BLDC motor has a trapezoidal BEMF (back electromagnetic force) induced into the
motor phase windings. The BLDC drive is also called trapezoidal control because of the
phase current shape. This control method allows having the maximum performance in
terms of efficiency and minimum torque ripple since the motor is intrinsically built as BLDC.
Figure 2: "six-step phase voltage with BEMF sequence and PWM modulation"
voltage applied to a phase (BEMF waveform and PWM modulation).
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Figure 1: BLDC motor control sequence

Figure 2: six-step phase voltage with BEMF sequence and PWM modulation

DocID029868 Rev 1
Figure 1: "BLDC motor control
UM2124
sequence"): the red
shows the